WS-Addressing

Web Services Addressing (WS-Addressing) is a specification of transport-neutral mechanism that allows web services to communicate addressing information. It essentially consists of two parts: a structure for communicating a reference to a Web service endpoint, and a set of message addressing properties which associate addressing information with a particular message.

WS-Addressing is a standardized way of including message routing data within SOAP headers. Instead of relying on network-level transport to convey routing information, a message utilizing WS-Addressing may contain its own dispatch metadata in a standardized SOAP header. The network-level transport is only responsible for delivering that message to a dispatcher capable of reading the WS-Addressing metadata. Once that message arrives at the dispatcher specified in the URI, the job of the network-level transport is done.

WS-Addressing supports the use of asynchronous interactions by specifying a common SOAP header (wsa:ReplyTo) that contains the endpoint reference (EPR) to which the response is to be sent. The service provider transmits the response message over a separate connection to the wsa:ReplyTo endpoint. This decouples the lifetime of the SOAP request/response interaction from the lifetime of the HTTP request/response protocol, thus enabling long-running interactions that can span arbitrary periods of time.

An endpoint reference (EPR) is an XML structure encapsulating information useful for addressing a message to a Web service. This includes the destination address of the message, any additional parameters (called reference parameters) necessary to route the message to the destination, and optional metadata (such as WSDL or WS-Policy) about the service.

Message addressing properties communicate addressing information relating to the delivery of a message to a Web service:

WS-Addressing was originally authored by Microsoft, IBM, BEA, Sun Microsystems, and SAP and submitted to W3C for standardization. The W3C WS-Addressing Working Group has refined and augmented the specification in the process of standardization.

WS-Addressing is currently specified in three parts:

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